Add command-line switch for no logo

[johncrim]

Consider adding a --nologo switch for command-line builds, which skips the ASCII art output. It's not useful in build logs.

[daveaglick]

FYI - the original Wyam project is being moved to statiqdev to continue work there as Statiq Web (the successor to Wyam and the Wyam blog recipe). Since this issue relates specifically to Wyam, I've transfered it to a new replacement project for legacy Wyam issues.

[daveaglick]

By the way - I hear you. In fact I did not include an ASCII art logo in Statiq for this very reason.